The present invention relates to medical devices. More particularly, the invention relates to an intravascular filter removal device that can be used to assist in the removal of a filter from the vena cava of a patient.
Filtering devices that are percutaneously placed in the vena cava have been available for a number of years. A need for such filtering devices arises in trauma patients, orthopedic surgery patients, neurosurgery patients, or in patients having medical conditions requiring bed rest or non-movement. Patients having such medical conditions face an increased risk of thrombosis in the peripheral vasculature, wherein thrombi break away from the vessel wall, risking downstream embolism or embolization. For example, depending on the size, such thrombi pose a serious risk of pulmonary embolism wherein blood clots migrate from the peripheral vasculature through the heart and into the lungs.
Historically, vena cava filters were considered to be permanent implants and remained implanted in the patient for life. More recently, removable vena cava filters have been developed. These filters may be removed from the patient's vena cava after the condition or medical problem that required the device has passed.
A particular problem that can arise during deployment of the filter or during treatment is misalignment of the filter. Many removable vena cava filters are manufactured with a removal hook at their proximal end. A physician or surgeon removing the filter can use a 2D imaging system to guide a looped snare to this hook, snare the hook, dislodge the filter from the vessel wall, and remove the filter from the patient's body.
Removal can be hindered or rendered impossible by minimally invasive means if the filter has become tilted during treatment. A practitioner may not be able to snare the hook of a tilted filter because some portion of the hook may have made contact with the vessel wall and in some cases the vessel may have grown around it. In this case, methods that are less precise and more invasive than simple snaring, such as dislodging the filter with forceps, may have to be employed.
Development of a more elegant means of removing a tilted vena cava filter has proven difficult.